Housing construction for multiple tap transformer



Jlm 3, 1969 O O DERlPPE 3,448,422

HOUSING CONSTRUCTION FOR MULTIPLE TAP TRANSFORMER Filed Oct. 25. 1965 Sheet of 2 FIG/I 55 2 3 B 8 PM 1 BY QM J. M. DERIPPE June 3, 1969 HOUSING CONSTRUCTION FOR MULTIPLE TAP TRANSFORMER Sheet Filed 001;; 23. 1965 FIG.3

8 57 2 33 v 2 wf w 2 o 8 3 3 9 2 I n. 2 6 C 68 2 3 33 6 6 1 4 M ve/vrae United States Patent 3,448,422 HOUSING CONSTRUCTION FOR MULTIPLE TAP TRANSFORMER Jean Marie Derippe, Aix-les-Bains, France, assignor to Compagnie Generale dElectricite, Paris, France Filed Oct. 23, 1965, Ser. No. 503,871 Claims priority, applicationlgrance, Dec. 14, 1964,

Int. Cl. H01r27/02, 27/12 U.S. Cl. 336-94 14 Claims ABSTRACT OF THE DISCLOSURE The present invention relates in general to transformers having multiple taps or connections connected to a live regulating or switching device for selecting various coil combinations. The live regulating device may be of any desired type and may comprise, for example, a tap preselector and a live switch for the taps chosen by the preselector.

The present invention is concerned, more particularly, with transformers comprising a regulating device to which a voltage is directly applied disposed at the outside of the principal tank enclosing the transformer, including the magnetic circuit and windings, the tank being filled with oil in the conventional manner.

As is known from the previous patents issued to applicant (French Patent No. 1,382,245 of Nov. 4, 1963, and French Patent No. 985,286 of Aug. 14, 1964), the construction and maintenance of transformers of the type described hereinabove have a number of different inherent problems. As far as the construction is concerned, the problems consist of reducing the volume of the tank surrounding the transformer and the total volume of the entire unit as much as possible, of reducing the length of the electric connections, of decreasing the number of the necessary high voltage lead-throughs for the housing and of providing suflicient means for assuring the fluidtightness of these lead-throughs and of generally reducing the complexity of the required mechanical elements associated therewith.

The regulating device utilized with transformers of the type described comprises generally a live switch whose operation is known to result in a pollution of the oil in which it is immersed and thus it is important to prevent any sizable or significant quantity of polluted oil from penetrating through to the active part of the transformer. One of the solutions previously proposed consists of creating a fluid-tight insulating wall between the tank containing the regulating device and the tank containing the transformer. Another solution comprises accommodating each of the two elements in one of two distinct compartments of the housing separated by means of a wall positioned at the inside of the tank, this wall being provided with an aperture disposed at the lower part thereof so as to allow for the passage of the necessary connections from the transformer to the regulator while limiting as much as possible the interchange of oil therebetween.

None of the previously proposed solutions mentioned above has satisfactorily solved the aforementioned problems, nor the problems arising in connection with .the maintenance of the apparatus. As a matter of fact, the live regulating device comprises movable mechanical elements which are constantly subjected to wear, and include conductive or insulating elements which may have to be replaced from time to time, and so it is of importance that a ready access be provided thereto without having to disassemble the entire unit of the transformer or to drain off the oil, necessitating a refilling of the active part of this transformer each time.

On the other hand, the maintenance of the transformer itself necessitates the removal of the principal tank or removal of the transformer from the tank, which should be carried out with a minimum of disassembling or disturbance to the live regulating device.

Finally, it is advantageous to have access to the active part of the transformer without having to disconnect the conductors connected to the taps of the windings, and to make it possible to disassemble the live regulating device completely without draining off the principal tank of the transformer.

The present invention has the object of providing a unitary transformer including a live regulating device which avoids the inconveniences of the heretofore known units and which proposes a solution for the problems mentioned hereinbefore.

The transformer having multiple taps with a regulating device therefor according to the present invention is characterized by a construction wherein the transformer is immersed into a main tank having a lateral wall including an aperture which is enclosed by first and second elementary shells, positioned respectively at the outside and at the inside of said tank and secured with the edges thereof on the tank, surrounding said aperture, for the purpose of forming an envelope or enclosure, wherein the regulating device is immersed in oil, which device is connected to said multiple taps by connecting conductors passing through a wall of the elementary shell positioned at the inside of the tank.

It is thus no longer necessary to remove the transformer from'the tank, nor to discharge its tank in order to effect a complete examination of the regulating device, not only with respect to its live switch but also with respect to the preselector terminals, which comprise mechanical elements subject to wear and tear.

Furthermore, the present invention makes it possible to accommodate the regulating device at the outside of the tank of the transformer with minimum increase in size of the overall transformer construction and without the secondary elementary shell positioned at the inside of the tank of the transformer markedly reducing the free space therein. Moreover, the small cavity or pocket formed at the outer surface fo the tank of the transformer by the second elementary shell makes it possible to accommodate therein the part of the connecting conductors which emerge from the tank of the transformer which are exposed when the regulating device is disassembled. This small cavity or pocket may then be closed in a fluid-tight manner by a simple partition and filled with oil. It is thus possible to provide each of the connecting conductors of uniform length .and to maintain the insulation thereof impregnated with oil, without having to fear that the insulation might lose the impregnating oil thereof after the regulating device has been disassembled.

According to a proposed embodiment of the present invention, the part of the wall of the second shell which is traversed by the connecting conductors is. oriented in such a manner as to be perpendicular to these conductors at the points where they pass through the wall, these conductors being thus disposed so as to reduce the number Patented June 3, 1969 of bends and turns therein along their path. This last disposition makes it possible to avoid the supplementary bends or curves in the conductors which would be necessary for mounting the lead-through elements perpendicularly to the lateral wall of the tank of the transformer. It is thus possible to reduce the length of the connecting conductors and, consequently, the total overall dimensions of the transformer assembly.

According to a particular feature of the present invention, said second elementary shell, positioned at the inside of the tank of the transformer, -is mounted thereon with fastening means rendering this second shell essentially integral with the magnetic circuit of the transformer and of its windings, independently of the lateral wall of the tank. Thanks to this provision, the transformer may be removed from the tank with the connecting conductors after the disassembly of the regulating device and of the fastening means between said second shell and the lateral wall of the tank of the transformer. The part of the connecting conductors which is positioned at the'outside of the tank of the transformer will then be accommodated in the small cavity or pocket formed by the second elementary shell and will no longer oppose the removal of the transformer from the tank.

According to one of the features of the present invention, the second elementary shell which is positioned in the tank of the transformer comprises a wall made of an insulating material, at least in the part thereof which is traversed by said connecting conductors. The leadthrough of the connecting conductors may particularly be constituted by simple bushings, or insulated connectors through an aperture sufficiently fluid-tight to avoid an exchange or interchange of oil, which would result in a detrimental pollution of the transformer oil.

The lead-through of the conductors may equally be positioned at the lower part of the enclosure or envelope formed by the first and the second elementary shells making it possible to provide said lead-throughs without any fluid-tightness, while at the same time allowing for the possibility of partially draining off the oil contained in the first and the second elementary shells to the level of these lead-throughs, the tank of the transformer then being provided, above this level, with closing means making it possible to render the tank fluid-tight during the partial drainage of the envelope or enclosure formed by the first and second shells.

These and other objects, features, and advantages of the present invention will be more apparent from the following detailed description of the invention when taken in conjunction with the attached drawings which illustrate two embodiments of the invention and wherein:

FIGURE 1 is a sectional view partially schematic of a triphase multiple tap transformer having a regulating device associated therewith in accordance with the invention, taken along line A-A' of FIGURE 2;

FIGURE 2 is a transverse cross-sectional view taken along line B-B' of FIGURE 1, and

FIGURE 3 is a 'view similar to that of FIGURE 1 of a modification of the triphase multiple'tap transformer having a regulating device associated therewith in accordance with the invention.

These examples disclosed herein are concerned with transformers whose active part comprises a magnetic circuit upon which are mounted three windings 1, 2 and 3 for the three phases and having multiple taps associated therewith. The active part of the transformer illustrated in FIGURES 1 and 2 is immersed into a tank which comprises an envelope 8 having a bell shape, or any other conventional configuration, secured with the lower part thereof, by means of a flange joint 9, to a base plate 7 in the form of a shallow receptacle upon which the active part of the transformer is mounted.

According to one embodiment of the present invention, as seen in FIGURES 1 and 2, one of the side walls of the tank 8 is provided with a rectangular aperture 51. A

first elementary shell 52 is positioned at the outside of the tank so as to enclose the aperture 51 and is secured to the wall of the tank 8 around the edges of the aperture. This attachment is effected by means of an L-shaped frame 53, or other suitable securing means, which is soldered to the wall of the tank 8 around the aperture 51. The frame 53 and the elementary shell 52 provide opposing surfaces which form a flange joint 54, tightened by means of bolts or other securing devices (not shown) so that this attachment allows for an easy and rapid assembly and disassembly of the elementary enclosure 52.

A second elementary shell 55 is positioned at the inside of the tank and surrounds the aperture 51 with inwardly turned edges so as to form a flange joint 56 by means of which the shell 55 is attached to the side wall of the tank 8 around the edges of the aperture 51.

The two elementary shells 52 and 55 constitute an envelope or enclosure into which is immersed a regulating device 13 which may include, for example, a live switch. The regulating device may be immersed directly into the oil in the space formed by the shells 52 and 55; however, in most cases, at least a part of the regulating device, for example the live switch, is placed into a separate fluidtight tank which is provided with oil by an expansion vessel 28 forming part of a reservoir 27. The device 13 may also include a connecting box 14 for the conductors connected to the taps, which connecting box may be coaxial with the live switch 13.

The oil reservoir 27 includes a partial internal partition 33 defining two compartments 28 and 28; the compartment 28" is connected by means of a gas-detecting relay 39 to two conduits 35 and 36 connected respectively to the regulating valves 37 and 38, and also connected to the active part of the transformer defined by the housing 8 and the enclosure defined by the shells 52 and 55,

- respectively. The compartment 28 of the reservoir 27 is connected only to the tank surrounding the live switch 13 by means of the conduit 30 in series connection with valve 32. Due to the existence of the partition 33 providng a separation of the supply circuits, the oil contained 1n the tank of the live switch cannot be mixed with the contaminated oil contained in the space between the shells 52 and 55 and in the active part of the transformer. The connection between the terminals of the connecting box 14 and the different multipletaps or connections of the windings 1, 2 and 3 is obtained by means of the strips of conductors 4, 5 and 6, respectively. They penetrate or extend into the elementary shell 55 through an insulating bushing which is secured in a fluid-tight manner within an aperture in one of the walls of the shell 55. In spite of the illustrated construction in the FIGURES, it is obviously not necessary that the conductor strips 4, 5 and 6 be superimposed and positioned directly upon each other at the inside of the tank.

It will be noted that the elementary shell 55 may :be so provided and arranged that the insulating bushing 23 thereof is positioned and oriented so as to facilitate the provision of the connecting conductors over their path or course between the multiple taps and the regulating device. The elementary shell 55 may, moreover, comprise several insulating bushings 23, for example one for each connecting conductor, and these different insulating bushings 23 may be oriented differently so as to facilitate the provision of these connecting conductors. It is thus possible to reduce the curves and bends in the connecting conductors. This makes it possible to particularly reduce the length of the connecting conductors and to increase the space which is left free within the housing.

The provision of the shells 52 and 55 according to the above-described construction aids in reducing the dimensions of the tank which, according to the provision and arrangement described herein, contains only the active part of the transformer without the presence of the shell 55 substantially effecting the space which is left free. The regulating device is thereby positioned at the outside of the tank without the total overall dimensions thereof being considerably increased.

One of the principal advantages of the construction in accordance with the invention resides in the capability for complete disassembly of the regulating device without making it necessary to drain olf the main transformer tank, even partially. It is suflicient to disassemble the flange joint 54 by means of which the elementary shell 52 is attached to the side wall of the tank and to disassemble the connections to the connecting box :14 of the regulating device. The elementary shell 55 then forms a small cavity or pocket opening out from the side wall of the tank of the transformer. The exposed extremities of the connecting conductors which emerge from the tank through the insulating bushing 23 may thus be accommodated in this small cavity or pocket and may be enclosed therein by closing the same by means of a simple partition attached to the edges of the frame 53 soldered on the tank. Each of the connecting conductors may thus be provided of a single length extending through the insulating bushing 23. This conductor may be provided over the entire length thereof with an oil-impregnated insulation and due to the ability to enclose the conductors during removal of the regulating device, there is no need to fear that this insulation 'will lose its impregnating oil after the disassembly of the regulating device. The small cavity or pocket formed by the elementary shell 55 may, in fact, be filled with oil after having been closed off, as has been stated hereinbefore.

On the other hand, the active part including the windings and magnetic cores of the transformer may be removed from the tank 'without making it necessary to disassemble the connection between the connecting conductors 4, and 6 and the multiple taps of the windings (not shown). As has been shown in FIGURE 1, the elementary shell 55 is provided as an integral part of the active portion of the transformer. A first fastening means, schematically illustrated as a rod 57, connects the magnetic circuit to a lug portion 58 which is secured to the upper part of the elementary shell -55. The lower wall of the shell 55 is in turn secured to a support 59 by means of suitable lug portions (not visible in the drawing) which are, in turn, secured to the base plate 7.

As should be apparent, the construction in accordance with the invention makes it possible to proceed with the removal from the tank of the active part of the trans former by accommodating in the shell 55 the extremities of the connecting conductors which emerge from the insulating bushing 23 toward the regulating device. For this purpose, one first proceeds with the disassembly of the elementary shell 52, with the disassembly of the regulating device and the connections thereof with the connecting conductors, and with the disassembly of the flange joint 56 of the elementary shell 55. The free extremities of the connecting conductors which emerge or issue from the insulating bushing 23 are then bent into the small cavity or pocket formed by the elementary shell 55 and the removal from the tank of the active part may then be carried out without difliculty by withdrawing the transformer and shell 55 as a unit.

Due to the arrangement of elements provided by the invention, the passages of the connecting conductors from the tank 8 to the envelope or enclosure defined by the shells 52 and 5-5 surrounding the regulating device do not require high-voltage lead-through bushings. It suffices to assure the fluid-tightness of the passage through the insulating partition 23 by means of simple packing, insulating boxes or any other fluid-tight means. In addition, it is not always necessary that this fluid-tightness be absolute and strict. It may sufiice that the oil exchanges between the two envelopes or enclosures be slow enough to involve only small quantities over a period of time. The disassembly of the regulating device no longer requires a strict and absolute fluid-tightness of the passage of the conductors through the bushing 23-. It suffices to limit the oil loss which may be produced during the disassembly until the small cavity or pocket formed by the shell 5'5 is closed off.

According to a modified embodiment shown in FIG- URE 3, the passage of the connecting conductors from one enclosure to the other may even be effected without any fluid-tight means for the conductors by means of a simple aperture through the elementary shell properly positioned at the inside of the tank of the transformer.

The elements of this modified embodiment which are identical with those illustrated in the embodiment of FIG- UR ES l and 2 have been designated with similar reference numerals. Similarly, the active part of the transformer comprises a magnetic circuit upon which are mounted three windings l1, 2 and 3 for a three phase voltage. A tank 8 encloses this active part and is secured by means of a flange joint 9 to a base plate 7 in the form of a shallow receptacle. A side wall of the tank 8 includes a rectangular aperture '51 as in the embodiment of FIG- URES 1 and 2.

'In this embodiment a shell positioned at the inside of the tank 8 surrounds the aperture 51 and is secured to the wall of the tank around the aperture by means of a flange joint 56. This shell 1155 does not comprise an insulating bushing but is provided only 'with a simple aperture 123 which is positioned at the lower part of the shell and through which extend-without fluid-tight meansthe connecting conductors being grouped together into a strip or bundle 124-.

A shell 1'52 positioned outside of the tank, as in the preceding example, surrounds the aperture 5 1. of the tank, but it is soldered directly on the tank 8 with the edges thereof, around the aperture 51. The shell 1'52 is constituted of two parts having a removable cover or lid. These two parts are assembled by means of a flange joint 163 positioned in an oblique plane determined so that, after the disassembly or removal of the cover, the inner part of the shell is accessible through an aperture whose lowest point is at a level higher than the highest point of the aperture bushing 123 through the shell 155. The regulating device 13' is enclosed in an envelope formed by the two shells 152 and 155. A reservoir 27 is connected similarly to this envelope and to the tank -8 by a gas relay 39, tubulures .3 5 and 36, and gates 37 and 38. One compartment 28 of the reservoir formed by the partition 30 is connected to a tank of the live switch.

It thus suffices for the purpose of proceeding with the removal from the tank of the regulating device to hermetically seal the gate 37 so as to insulate the tank 8 of the reservoir 27. It is then possible to drain off the space between the two shells 1'52 and '155 upto the higher level of the aperture 123 and disassemble or remove without difficulty the cover or lid 1 62.

While I have shown and described several embodiments in accordance with the instant invention, it is understood that the same is not limited thereto but is susceptible of many changes and modifications within the spirit and scope thereof, and I therefore do not wish to be limited to the details shown and described herein, but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

Iclaim: v

1. A housing for multitap transformer construction having an active portion including a plurality of windings and magnetic cores for said windings and a regulating device for controlling the connection to said windings, said housing comprising:

a first closed tank enclosing the active portion of said transformer construction including a base element directly supporting said active portion and an upper element having side walls surrounding said active portion substantially along the entire height thereof,

a second closed tank comprising inner and outer shells releasably secured to opposite sides of a lateral wall of said upper element in face-to-face relationship,

said lateral wall being provided with an aperture effecting communication between the spaces defined by said shells,

said regulating device being mounted within said second closed tank, said first and second tanks being substantially filled with oil, and

conductor means passing from said first tank into said second tank connecting said windings to said regulating device.

2. A housing for a multitap transformer construction as defined in claim 1 wherein said conductor means is dis posed substantially perpendicularly to the wall of said inner shell, said wall of said inner shell extending at an angle to said lateral wall of said upper element so as to provide a substantially straight course for said conductor means between said windings and said regulator device.

3. A housing for a multitap transformer construction as defined in claim 1 further including first fastening means for interconnecting said active portion of said transformer to said inner shell and second fastening means releasably securing said inner shell to said upper element.

4. A housing for multitap transformer construction as defined in claim 1 further including insulating leadthrough bushing means secured to a wall of said inner shell, said conductor means passing through said bushing means and being hermetically sealed thereto.

5. A housing for a multitap transformer construction as defined in claim 1 further including an aperture disposed in the lower portion of a wall of said inner shell for accommodating the passage of said conductor means from said first tank to said second tank, and removable cover means disposed in the upper part of said outer shell with the lowest point thereof positioned at slightly above the highest portion of said aperture in said inner shell.

6. A housing for a multitap transformer construction as defined in claim 5 wherein said cover means is disposed at an oblique angle within said second tank and includes an aperture accommodating said regulating device.

7. A housing for a multitap transformer construction as defined in claim 1 further including a third tank enclosing said regulating device and supported within said second tank, said third tank being filled with oil and including hermetically sealed passage for passing said conductor means through said tank.

8. A housing for multitap transformer construction as defined in claim 7 further including oil reservoir means for supplying oil to said first, second and third tanks including first and second isolated compartments containing oil, first valve means connecting said first compartment only to said third tank and second valve means connecting said second compartment only to said first and second tanks.

9. A multitap transformer construction having an active portion including a plurality of windings with taps and magnetic cores for said windings and a regulating device for controlling the application of voltage to said taps, the improvement esentially consisting of a housing for said transformer construction, comprising:

a first closed tank enclosing the active portion of said transformer constuction,

a second closed tank disposed partially within said first closed tank and enclosing said regulating device, said first and second tanks being substantially filled with oil, and

conductor means passing from said first tank into said second tank connecting said taps to said regulating device,

wherein said second tank comprises inner and outer shells releasably secured to opposite sides of a lateral wall of said first tank in face-toface relationship, said lateral Wall including an aperture efiecting communication between the spaces defined by said shells.

10. A multitap transformer construction as defined in claim 9 further including first fastening means connecting said inner shell to said active portion of said transformer and second fastening means releasably securing said inner shell to said lateral wall of said first tank.

11. A multitap transformer construction as defined in claim 1 further including lead-through bushing means secured to a wall of said inner shell, said conductor means passing through said bushing means and forming a hermetic seal therewith.

12. A multitap transformer construction as defined in claim 9 further including an aperture disposed in the lower portion of a wall of said inner shell for accommodating the passage of said conductor means from said first tank to said second tank, and partition means obliquely disposed in said outer shell and having an aperture therein through which said regulating device extends, said aperture in said partition means being disposed above the aperture in said inner shell.

13. A multitap transformer construction as defined in claim 9 further including a third tank within said second tank and enclosing said regulating device.

14. A multitap transformer construction as defined in claim 13 including first and second sources of oil, said first source of oil being connected only to said third tank and said second source of oil being connected only to said first and second tanks.

References Cited UNITED STATES PATENTS 1,940,311 12/1933 Lennox 33694 2,541,236 2/1951 Giuifrida 174-18 2,915,720 12/1959 Mueller et al 336 X 2,960,672 11/1960 Kowalschitsch et al. 336-105 X 3,041,560 6/1962 Sealey 336105 X OTHER REFERENCES 813,464 5/1969 Great Britain.

LEWIS H. MYERS, Primary Examiner.

T. J. KOZMA, Assistant Examiner.

US. Cl. X.R. 

